Delivery devices for the delivery of fluids at predetermined flow rates are well known in the art. The delivery of fluids at rates of below approximately 30 milliliters per minute typically involve the use of devices such as syringe pumps. While such devices are suitable for regulating very low rates of flow, they generally are not adequate for flow rates above 30 milliliters per minute. The delivery of fluids at rates above approximately 200 milliliters per minute typically includes the use of flow meters. However, such devices are generally unsuitable for flow rates below 200 milliliters per minute. Thus, it is difficult to use conventional devices to produce flow rates in the range of approximately 30-200 milliliters per minute.
Conventional flow meters and pumps provide the additional disadvantage that such devices include moving elements involving chemicals that may interfere with the purity and chemical characteristic parameters required in certain industries, such as the semiconductor fabrication or medical industries. Noninvasive flow meters that do not interfere with the required purity and chemical characteristics parameters, such as vortex meters, Corioles meters, ultrasonic meters, magnetic flow meters and the like, are typically large, closed-loop units that take up valuable space.
Thus, there is a need for a compact, open-loop fluid metering device that is suitable for delivering fluid at constant rates in the range of approximately 30-200 milliliters per minute. There is a further need for a fluid metering device that will not interfere with the purity and chemical characteristic parameters of the fluid during flow.